The invention relates to a device for protecting a motor vehicle against unauthorized use by third parties, by means of a driving-authorization detection arrangement which takes person-specific features into account.
Devices which protect against unauthorized use by third parties and prevent vehicle starting are known, in which at least one piece of vehicle equipment required for driving is adjusted, when the vehicle is parked, to a state which disables the starting of the vehicle. The disabled state can be cancelled by means of a vehicle authorization signal that can be triggered only by means of a code signal of an authorizing, user-end key unit. Such disabling arrangements suffer, however, from the problem that an unauthorized person can forcibly gain authorization by stealing the authorizing key unit or threatening the authorized person to reveal the authorizing code. Devices for protecting against use by third parties of the type mentioned at the beginning attempt to overcome this problem by closely associating the driving authorization criterion with the identity of the authorized person.
Such a device for protecting against use by third parties is described in the German Patent Document DE-OS 35 14 241 A1, in which an image of a grooved area of the driver's skin (in particular a finger tip), is recorded using a video camera. For this purpose, the camera is focused onto the surface of an exterior viewing screen, and the area of skin is placed on the screen and illuminated from the camera side when the image is recorded. The information on the grooved skin structure thus obtained is compared in an identification unit with an item of stored desired grooved skin structure information. If correspondence is detected a driving authorization signal is generated which actuates a disabling circuit that otherwise disables a piece of equipment required to operate the vehicle (for example, steering lock, ignition or fuel supply unit). The execution of a detection process is required for each subsequent successful start of the vehicle. In order to increase security against manipulation in the case of an attempt to bring about a successful detection process by using a photograph of the respective skin area of the authorized user, there is provision for an image to be recorded under different lighting conditions and for evaluation of the shadow structures which vary in such a case.
However, the security of this system is limited in that an unauthorized person can obtain unlimited future driving authorization by, for example, forcing the authorized person to provide him with a copy of the respective skin groove structure with which he can make a plastic copy to be used subsequently to achieve driving authorization. Additionally, this system requires additional action on the part of the driver before the vehicle starts in the form of the positioning of the skin area on the viewing screen, which makes the starting process less convenient.
To identify a specific person, in addition to taking finger prints, it is also known to compare an image of the eye (for example, of the iris and pupil area or of the area of the cornea), and compare it with corresponding stored image information. For this purpose, the person to be tested has to look into a scanning device such as provided, for example, in the laid-open publication WO 86/05018 or the magazine article "Aufeinen Blick [with one look]" in Funkschau 1/1987, page 34. Yet another identification arrangement compares an image of a facial area which is compared with stored image information by means of an image processing unit on the basis of a neuronal network. This arrangement can identify an individual even in the case of slightly changed image information, for example as a result of a slightly different posture of the head, changed hairstyle or different facial expression. See the newspaper report "Fingerabdruck wird zum Schlufssel [finger prints become the key]" in VDI Nachrichten No. 3, 22.01.1993, page 13, and the article "Distortion Invariant Object Recognition in the Dynamic Link Architecture" by M. Lades et al. in IEEE, TRANS. ON COMP., Vol. 42, No. 3, March 1993, page 300.
U.S. Pat. No. 4,625,329 discloses a device for detecting the position of a vehicle driver, in which the face of the driver is illuminated and the light reflected back from it is received and evaluated in order to determine the three-dimensional position of the driver. The purpose of this device is to automatically adjust to the particular driver, certain adjustable vehicle elements, such as the rearview mirror, air vents etc. Thus, in this publication, only the position of the facial area of the driver is monitored in space, without object-detecting image analysis of the facial area.
An object of the present invention is to provide a device for protecting a vehicle against use by third parties, which permits reliable detection of an authorized driver, is comparatively manipulation-proof and is convenient.
This problem is solved according to the invention, by means of a device which utilizes image analysis of an area of the face for driving authorization detection. Such image analysis of facial features is sufficiently functionally reliable for this purpose, given the currently available object detection systems which are neuronal networks, since the image processing of such an object detection system is capable of recognizing the area of the face even in the case of a somewhat changed external appearance (for example changed posture of the head, different glasses and different facial expression), and is also capable of reliably distinguishing the area of a face from corresponding areas of faces of other persons. In particular, it is expedient to include the region of the eyes, nose and mouth in the analyzed area of the face.
The high selectivity of such a facial area detection system provides at the same time a high degree of protection against manipulation, since it is virtually impossible for an unauthorized person to produce a satisfactory copy of an authorizing area of a face. Additionally, the device is extremely convenient, since the suitable positioning of the camera which records the images eliminates the need for any actions on the part of the driver in order to verify driving authorization. Instead, the detection process proceeds completely automatically, without the driver having to devote his attention to it detection at all. That is, the driver can activate the vehicle and keep it operating, without being disturbed by the detection of driving authorization.
Parallel to the detection of driving authorization by image analysis of an area of a driver's face, further conventional security devices may also be provided within the entire system of the device for protecting against use by third parties. In particular systems may be provided for detecting access authorization, such as a mechanical and/or an electronic key with electronic access authorization coding.
One embodiment of the invention further increases security against manipulation by detecting the thermal radiation of the facial area, so that, for example, even an externally identical mask copy of the authorizing facial area does not lead to a driving authorization signal being generated.
Increased security against manipulation is also offered by another embodiment of the invention in which, when an authorized driver is actually seated at the steering wheel of the vehicle while driving it, the images of the facial area are successively recorded. Such images are never completely identical because of the different posture of the head and facial expression, and the vehicle, in this case, is not disabled. If, on the other hand, an unauthorized person attempts to feed manipulated image information into the image processing unit, the device is able to recognize this image information which is present in unchanged form, as manipulated input information and, in response, to disable the vehicle to prevent further use. Moreover, since it is not absolutely necessary in this case to detect driving authorization before an attempt to start the vehicle, it may be possible, if appropriate, to save on computational outlay. of course, it is possible by means of further measures to ensure that other kinds of manipulation attempts carried out on the camera or on the evaluation system also lead to subsequent deactivation of the vehicle. It is also possible to preclude restarting of the vehicle until the system has been reprogrammed with original image information.
In another embodiment of the invention a sitting position is preprogrammed for the driver so that his or her facial area can be reliably positioned in the spatial area detected by the video camera before a detection process is carried out, without the driver having to concern himself with this requirement. After detection of driving authorization, he may then, if appropriate, perform further seat adjustment. Preferably, the system stores the seat position when the vehicle is parked as a desired position for the next time this user enters the vehicle. At the same time, if the image recording camera is movable, the position of the camera can also be stored and matched to the facial area, making the facial-area detection process in the image processing unit easier since serious longitudinal and transverse deviations of the position of the facial area during the recording of the images do not occur. Therefore, in vehicles with mechanical seat adjustment, the detection system may require a somewhat larger computational outlay in order to determine the position of the facial area. If necessary, when the seat adjustment is mechanical, a measure which increases driving safety, consisting in moving the driver into a suitable seat position before the vehicle starts, can be associated with the detection of driving authorization.
Still another embodiment of the invention prevents manipulation of the signal line between the camera and image processing unit by entering manipulated image information in place of actual image information into the image processing unit, in the same way as such information could be acquired for example by using a video image of an authorized person.
Further embodiments of the invention relate to coding measures for increased protection of the data flow for detecting driving authorization by means of optical testing of the facial area. Thus, storing the desired image information in a unit in the vehicle, it may be stored in a code-protected way in an electronic key unit carried by the user, so that the said information is not present in the vehicle and cannot be read out of the vehicle in an unauthorized way, even if the vehicle is stolen. Also, reading out the stored image information from a key unit prevents an unauthorized person's gaining access to the system without knowledge of the code used for storage.
The transmission of the desired image information into the image processing unit during activation of a facial-area detection process can also be performed in a code-protected way. For this purpose the same procedures can be applied as are used to transmit, from a key unit to the vehicle, code information which authorizes access or deactivates an immobilizer. In particular, the algorithm for decoding the code for the storage of desired image information may be stored in coded form in the key unit, and activated in response to a request from the vehicle by means of bidirectional exchange of data so that secret information does not need to be stored in the vehicle. If the decoding requires a significant amount of power, mechanical contact may be provided between the key unit and the power supply of the vehicle. Of course, a possible alternative is to store the algorithm in the vehicle, in particular integrated in the image processing unit.
In order to increase security further, an acknowledgement exchange method may be provided to prevent unauthorized reading out of the information at the key end. In this embodiment it is determined initially, by reference to a vehicle-specific code which is also stored in the key unit, whether the combination of key unit and vehicle is acceptable, and the actual exchange of code data relating to detection of driving authorization and possibly detection of prior access authorization, does not take place until this has occurred.
A further advantageous embodiment protects the transmission path of the driving authorization signal (which is generated in the image processing unit when correspondence of images is detected) to respective pieces of vehicle equipment, in order to prevent the direct entry of a manipulated signal to actuate these pieces of vehicle equipment to change into a state which permits starting of the vehicle. If, in this way, a plurality of pieces of equipment (for example, all the relevant control devices of the vehicle's electrical system), are protected against unauthorized enabling, it would be necessary to replace all of them in order to bypass the device for protecting against use by third parties. Consequently, the pieces of equipment can be selected such that the required outlay is no longer in reasonable proportion to the benefit which can potentially be achieved by a theft, and theft thus is unattractive.
In still another embodiment of the invention, after a successful detection of driving authorization, it is possible for the vehicle to continue to be used for a prescribed number of operating phases, even by persons for which no authorizing facial area information is stored. No further enabling signal is then produced until after this prescribed number of operating phases if the vehicle is not in the meantime, or subsequently, used again by an authorized driver. The intention of this measure is to permit the vehicle to be used temporarily even by persons other than those stored as authorized, which is desired for example for occasions when the vehicle is lent out, visits to garages and hire cars.
Another embodiment of the invention enables an authorized driver also to use the vehicle with other acceptable key units despite the facial area information being stored in the key, for occasions for example when he has lost a key unit.
In a final embodiment of the invention the detection security can be increased. At the same time, attempts at manipulation are made more difficult.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.